1. Field of the Invention
The present invention is directed to an apparatus having a transmission arrangement for the transmission of electrical energy and/or signals from an apparatus part to electrical devices which are displaceable relative to the apparatus part, the transmission arrangement including a reel onto which and from which a conductor can be wound.
2. Description of the Prior Art
For example, German Utility Model 89 09 486 discloses an apparatus of this general type. This known apparatus has two apparatus parts which are adjustable relative to one another and which are connected to one another by the conductor. The transmission arrangement, which is held in one of the two apparatus parts, includes an outer, hollow cylinder-like drum forming a reel that is seated so as to be rotatable around an inner hollow cylinder-like drum that is stationary relative to the outer drum. The respective outer surfaces of these drums have an opening through which the conductor, namely a ribbon conductor, is conducted.
The ribbon conductor is first conducted through a lateral opening of the inner drum, then through the opening in the surface of the inner drum into the region between the drums, and is wound around the inner drum as a helix, and is conducted toward the outside through the opening in the surface of the outer drum. The section of the ribbon conductor that is located between the drums thus has its section ends respectively secured to the inner and outer drums such that the ribbon conductor is wound onto the surface of the outer drum, or is unwound therefrom with the assistance of a guide given rotation of the outer drum around the inner drum. When the ribbon conductor is wound onto or unwound from the outer drum, the helix formed by the region of the ribbon conductor lying between the drums narrows or widens in the direction toward the surface of the inner drum.
Given an adjustment of the two apparatus parts of the apparatus relative to one another, a tensile force or thrust is thus exerted on the ribbon conductor secured to the other apparatus part, causing the outer drum to rotate and thereby effecting the winding or unwinding of the ribbon conductor.
German OS 40 19 513, corresponding to U.S. Pat. No. 5,145,390, discloses an apparatus having two apparatus parts which are adjustable relative to one another and which are connected together by an electrical conductor, which is again a ribbon conductor, and having an arrangement for the acceptance of the ribbon conductor and a cable, the arrangement being held in one of the two apparatus parts. The arrangement includes a rotatable drum onto which or from which the ribbon conductor and the cable, which are secured to the other apparatus part, namely at a one end of the other apparatus part, are wound or unwound in opposite directions on different regions of the drum. Upon exertion of a tensile force onto the ribbon conductor by adjusting the two apparatus parts relative to one another, the ribbon conductor is unwound from and the cable is wound onto the rotatable drum and, given exertion of a tensile force on the cable due to oppositely directed adjustment of the two apparatus parts relative to one another, the cable is unwound from and the ribbon conductor is wound onto the rotatable drum. A spring, by means of which the cable end is secured to the other apparatus part, thereby serves the purpose of exerting a constant tensile force on the cable, and thus on the ribbon cable as well, so that this is wound onto the drum with a slight pre-stress.
Because they operate by rolling up the cable, these known arrangements are structurally complicated devices that are only suitable for winding or unwinding a single cable reliably, i.e. without the formation of loops. Ultimately, they function reliably only with ribbon conductors. Ribbon conductors, however, are expensive and occupy a large space when wound onto a drum.